By default on a Mac OS X and other *nix systems, Terminal starts the shell via
/usr/bin/login, which makes the shell a login shell. On every platform (not just Mac OS X) bash does not use
.bashrc for login shells (uses only
/etc/profile and the first of
.profile that exists and is readable). This is why adding
source ~/.bashrc in your
.bash_profile usually works.
But if that doesn't work, try adding the settings to
HISTTIMEFORMAT="[%F %T] "
PROMPT_COMMAND="history -a; history -c; history -r; $PROMPT_COMMAND